Detent mechanisms are known and used in a clutch of an outboard motor so as to provide a detent feeling in response to an axial movement of a clutch member relative to a pair of opposed bevel gears. A typical example of the known detent mechanisms is disclosed in Japanese Patent Laid-Open Publication (JP-A) No. 11-222196 (corresponding to U.S. Pat. No. 6,132,272 issued on Oct. 17, 2000.
The disclosed detent mechanism is incorporated in a dog clutch of an outboard motor. The dog clutch includes a clutch dog member splined to a propeller shaft between a pair of driven bevel gears rotatably mounted on the propeller shaft. The driven bevel gears mesh with a driving bevel gear secured to the lower end of a drive shaft coupled to the crankshaft of an engine. The clutch dog member is slidably mounted on the propeller shaft and movable in an axial direction relative to the driven bevel gears.
The detent mechanism consists of a spring and balls that are accommodated in a hollow slide rod coupled to an end of the propeller shaft. By manually displacing the slide rod in an axial direction, the human operator can selectively cause the clutch dog member to engage with one, the other, or neither of the driven bevel gears to thereby select a desired shift position. In this instance, the detent mechanism gives the operator a detent feeling when any of the shift positions is selected.
When the clutch dog member is axially displaced in a direction to place one of crown gears formed on both axial end faces of the clutch dog member into meshing engagement with a mating one of crown gears formed on the driven bevel gears, it may occur that the crown gear of the clutch dog member and the meting crown gear of one driven bevel gear impinge together and generate unpleasant striking noise when they are subjected to torsional vibrations produced when the engine undergoes irregular combustion. In order to avoid the generation of striking noise, an attempt has been made to increase the weight of a flywheel attached to an engine crankshaft or to provide a torsion bar in a power transmission path. The prior attempt is not successful because due to complicated construction, it requires an additional cost, an increase in weight and a large installation space.
It is accordingly an object of the present invention to provide a clutch detent mechanism for an outboard motor, which is simple in construction but is able to preclude the generation of unpleasant striking noise from a dog clutch in which the clutch detent mechanism is incorporated.